Pseudo-obstruction

Question 1

What is pseudo-obstruction?

Answer 1

• Dilatation of colon due to adynamic bowel
• Absence of mechanical obstruction
• Most commonly affects caecum and ascending colon

Question 2

What is PO known as acutely?

Answer 2

Ogilvie syndrome

Question 3

Pathophys of pseudo-obstruction

Answer 3

• Interruption of autonomic nerve supply to colon
• = absence of smooth muscle action in bowel wall
• Leads to increased risk of ischaemia and perforation

Question 4

Causes of pseudo-obstruction

Answer 4

• Electrolyte imbalance or endocrine disorders - eg hypercalcaemia, hypothyroidism, low Mg2+
• Medication inc opioids, CCBs, antidepressants
• Recent surgery, severe systemic illness or trauma
• Neurological disease eg Parkinsons or MS

Question 5

Symptoms of pseudo-obstruction

Answer 5

• Abdominal distension
• Abdominal pain
• Absolute constipation
• Vomitting = late
• Can have concurrent illness eg infection/electrolyte imbalance

Question 6

Examination of pseudo-obstruction

Answer 6

• Distended abdomen
• Tympanic abdomen - gas filled
• Absent bowel sounds
• Signs of peritonism - suggest ischaemia

Question 7

Bedside and bloods for pseudo-obstruction

Answer 7

• FBC
• U&E
• Ca2+
• Mg2+
• TFTs

Question 8

Imaging for pseudo-obstruction

Answer 8

• CT scan abdomen pelvis + IV contrast
• Will show dilation of entire colon, no obvious narrowing/transition - so no mechanical obstruction
• AXR - bowel distension BUT cannot tell between pseudo and mechanical

Question 9

What to do if imaging unclear for diagnosis of pseudo-obstruction

Answer 9

• Endoscopic assessment eg flexible sigmoidoscopy
• = direct visualisation and concurrent bowel decompression for symptomatic relief

Question 10

Management of pseudo-obstruction - ALL

Answer 10

• IV deplete –> IV fluids
• NG tube if patient vomitting
• Urinary cathter for fluid balance
• Analgesia
• Correct electrolytes

Question 11

Conservative management pseudo-obstruction

Answer 11

If no resolution within 24-48hrs despite correcting any underlying cause:
* Decompression via flexible sigmoidoscopy and insertion of flatus tube

Question 12

What to do if sigmoidoscopy decompression does not work?

Answer 12

• Can try using IV neostigmine - anticholinesterase
• But must be in high dependency monitiored setting as severe bradycardia is side effect

Question 13

When is surgery required for patients with pseudo-obstruction?

Answer 13

• Evidence of bowel ischaemia
• Perforation
• Recurrent or non-responding cases

Question 14

Surgical management of pseudo-obstruction

Answer 14

• Lapartomy and subtotal colectomy - due to involvement of entire colon
• Less common - caecostomy or defunctioning ileostomy (if incompetent ileocaecal valve)